Tyre knowledge

[kentishvanman]

Hi,
Just read an article in a journal I receive which may be of interest. I have summarised it
Tyres. Tests show that tyres are only performing at 55% efficiency when they are down to the legal limit ie 1.6mm which means stopping distances are greatly increased in the wet. Would drivers tolerate this poor perormance from their or other peoples brakes.
Tyres are the only contact with the road. In the wet stopping distance from 50mph on a legal mininium tyre is 42' (13m) more than on a new tyre, almost 3 car lengths.
Two thirds of motorists don't know that 1.6mm is the minimium legal limit. 40% never check the tyre tread and 20% don't know how.
A staggering 80% of motorists felt their deteriorating tyres affecting their cars performance and stopping distance but it did not change their attitude to tyre checks.
There are recommendations that the legal limit be increased to 3mm which is the minimum on government and emergency services vehicles.
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It makes you think, I can stop but can the other bloke.
Hope this is of interest.
Don

[Bowton Lad]

There are recommendations that the legal limit be increased to 3mm which is the minimum on government and emergency services vehicles.

I think you will find that the 3mm aplied to emergency vehicles is self imposed rule (not law) due to the vehicles being driven harder than ordinary vehicles ie. harder braking/cornering etc in all weather conditions except snow. Fire appliances have there tyres changed when the tread gets down to 3mm because heavy commercial tyres don't expel water from the tread the same as cars, they don't have the very fine grooves that car tyres have.

[Jeff J]

I think ( well for me anyway) this is a very confusing issue. As tyres wear down there is still as much surface area of rubber in contact with the road surface as when they are new. The only time it I would have thought it makes a difference is in the wet as the shallower tread will not remove as much water. But any one with an ounce of common sense drives slower in the rain so therefore braking times are reduced anyway. So increasing a legal depth limit just makes money for manufacturers & retailers & does not improve safety. Guess I'm not one of the 80%

[kevtherev]

Tyres have a shelf life
Tyres have a use by date
Tyres have a fit for purpose end date

Cheap imported tyres do not conform to ISO standards of materials and construction.

Tyres are made for regions (Climate) to be fit for the conditions and road temperature ranges.

The more natural rubber contained in the tread the grippier it becomes.
The less rubber there is the more hard wearing it becomes. (very useful in off road conditions.)

Tyres made to ISO standards are tested way past their expected parameters.

Modern radial tyres have been developed from F 1 racing (ongoing)

All tyres are made from synthetic rubber (large percentage) and natural rubber mix.

Tyres are only black for cosmetic reasons.
Tyres would be off white if vast quantities of carbon black was not used.

It takes about 20 seconds to make a standard car tyre. (raw state)

I made tyres for 20 years

Natural rubber is very expensive, but it is the key to grip.
No other material either synthetic or otherwise has it's capabilites.
Imported tyres from unregulated countries have little or no natural rubber.
Manufacturers in Europe/USA have to conform to standards. These standards cost money. But what price do you put on your family?

Cheap tyres mean less grip.
That fact will not be known until your van slams into the back of a truck. When it would have stopped safely a while back.

[Wychall]

It takes about 20 seconds to make a standard car tyre. (raw state)

I made tyres for 20 years

You must be well "tyred" by now, Kev!

[California Dreamin]

I think ( well for me anyway) this is a very confusing issue. As tyres wear down there is still as much surface area of rubber in contact with the road surface as when they are new. The only time it I would have thought it makes a difference is in the wet as the shallower tread will not remove as much water. But any one with an ounce of common sense drives slower in the rain so therefore braking times are reduced anyway. So increasing a legal depth limit just makes money for manufacturers & retailers & does not improve safety. Guess I'm not one of the 80%

The old question of 'WHAT IS TREAD FOR?' as you quite rightly point out, it is mainly for dispelling water when raining.

When F1 cars want to go 'Fast' they fit slicks not treaded tyres....but then the surface of a GP track is near perfect tarmac.

Treaded tyres on road going vehicles are merely a compromise, they do all jobs (rain/snow and shine) moderately well but if we genuinely wanted the best tyres for any given road condition we would possible need 2 or even three sets of tyres and the dedication to change them everytime the conditions changed.....can't see that happening lol.....but then of course our northern european cousins have to fit 'winter wheels/tyres' at certain times of the year as their driving conditions vary too much for 'one tyre type' to cope with.
You could argue that our own 'Summer/Winters' are becoming more extreme, and that we need to adopt these same regulations.
Martin

[kevtherev]

On top of what martin says, is by the time the tread has worn down to it's lower level, the tyre has generally come to the end of it's life.
As by now the rubber in the tyre has lost the properties it was employed to do (grip, elasticity) due to it's degrading over time.
you can often see this in the form of cracks in the sidewall.
The chances of tread separation and sidewall failure increase after five-six years.